Field of the Invention
The present invention relates to spark plugs used for ignition of fuel gas in internal combustion engines and the like.
Description of Related Art
In a spark plug used for ignition in an internal combustion engine or the like, when a voltage is applied to a center electrode and a ground electrode which are insulated from each other by an insulator, a spark occurs in a spark gap formed between a front end portion of the center electrode and a front end portion of the ground electrode (e.g., Patent Document 1).